1. Field of the Invention
This application relates in general to an optical device and in particular to a lens module of a scanner.
2. Description of the Related Art
Operation of a camera scanner is more efficient than that of a conventional contact type scanner which reads images line-by-line. Referring to FIG. 1, a conventional camera scanner 1 comprises a housing 11, a lens module 12 disposed in the housing 11, and a light source 13. Light is emitted from the light source 13 to a document 14 and into the housing 11. Subsequently, light is reflected by several mirrors 15 to the lens module 12, thus projecting an image in the lens module 12.
Referring to FIG. 2, the viewing angle θ0 of the camera scanner 1 is about 40 degrees. Because the lens module 12 requires greater focal length to provide adequate viewing angles, dimensions of the camera scanner 1 must be large. To facilitate miniaturization of the camera scanner 1, adequate viewing angles of the lens module 12 must be achieved without large dimensions of the camera scanner 1.